1. Field of the Invention
The present invention relates to an apparatus and a method for processing an informational signal that are preferable for use in executing plural pieces of processing sequentially to an informational signal such as an image signal and an audio signal.
2. Description of Related Art
Meta-information for an image signal has been used relative to horizontal and vertical synchronous signals, a copy preventing signal, closed captioning, and the like. Among them, synchronous signals utilized in synchronous control operation are synchronous signals for displaying an image, and have no information for each field. Thus, the synchronous signals have information insufficient as to be utilized in a control operation for each field.
In the case where the time necessary for processing an image signal and the time necessary for processing an audio signal are processed by different methods from each other, there arises a time gap between the image created by the image signal and the audio created by the audio signal, namely, a so-called lip synchronization is failed.
For example, Japanese Patent Application Publication No. 2004-15553 discloses a technique for adjusting the lip synchronization. According to the technique disclosed in this publication, when a contents-receiver receives contents from a server at an encoder side and decodes the received contents, the contents are separated into an image packet and an audio packet that together constitute the contents, and then these packets are respectively decoded. After that, a video frame and an audio frame are output, based on the video time stamp added to the image packet and the audio time stamp added to the audio packet. In this manner, the image and the audio are output at the coincided timings with each other.